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</a></div> <!----></nav>  <ul class="sidebar-links"><li><a href="/base/" aria-current="page" class="sidebar-link">计算机基础</a></li><li><section class="sidebar-group collapsable depth-0"><p class="sidebar-heading open"><span>算法</span> <span class="arrow down"></span></p> <ul class="sidebar-links sidebar-group-items"><li><a href="/base/algorithm/" aria-current="page" class="active sidebar-link">算法</a><ul class="sidebar-sub-headers"><li class="sidebar-sub-header"><a href="/base/algorithm/#推荐学习" class="sidebar-link">推荐学习</a></li><li class="sidebar-sub-header"><a href="/base/algorithm/#什么是哈希表" class="sidebar-link">什么是哈希表？</a></li><li class="sidebar-sub-header"><a href="/base/algorithm/#实例" class="sidebar-link">实例</a></li></ul></li><li><a href="/base/algorithm/array.html" class="sidebar-link">数组相关</a></li></ul></section></li><li><section class="sidebar-group collapsable depth-0"><p class="sidebar-heading"><span>HTTP</span> <span class="arrow right"></span></p> <!----></section></li><li><section class="sidebar-group collapsable depth-0"><p class="sidebar-heading"><span>Linux</span> <span class="arrow right"></span></p> <!----></section></li></ul> </aside> <main class="page"> <div class="theme-default-content content__default"><h1 id="算法"><a href="#算法" class="header-anchor">#</a> 算法</h1> <ol><li>数组去重</li> <li>数组排序</li> <li>数组扁平化</li> <li>斐波那契数列</li> <li>输出所有和N的连续正数序列</li> <li>最大蓄水池问题</li> <li>找零问题、背包问题、凸包问题</li></ol> <h2 id="推荐学习"><a href="#推荐学习" class="header-anchor">#</a> 推荐学习</h2> <ul><li>堆栈、队列、链表：<a href="https://juejin.im/entry/58759e79128fe1006b48cdfd" target="_blank" rel="noopener noreferrer">https://juejin.im/entry/58759e79128fe1006b48cdfd<span><svg xmlns="http://www.w3.org/2000/svg" aria-hidden="true" focusable="false" x="0px" y="0px" viewBox="0 0 100 100" width="15" height="15" class="icon outbound"><path fill="currentColor" d="M18.8,85.1h56l0,0c2.2,0,4-1.8,4-4v-32h-8v28h-48v-48h28v-8h-32l0,0c-2.2,0-4,1.8-4,4v56C14.8,83.3,16.6,85.1,18.8,85.1z"></path> <polygon fill="currentColor" points="45.7,48.7 51.3,54.3 77.2,28.5 77.2,37.2 85.2,37.2 85.2,14.9 62.8,14.9 62.8,22.9 71.5,22.9"></polygon></svg> <span class="sr-only">(opens new window)</span></span></a></li> <li>递归：<a href="https://segmentfault.com/a/1190000009857470" target="_blank" rel="noopener noreferrer">https://segmentfault.com/a/1190000009857470<span><svg xmlns="http://www.w3.org/2000/svg" aria-hidden="true" focusable="false" x="0px" y="0px" viewBox="0 0 100 100" width="15" height="15" class="icon outbound"><path fill="currentColor" d="M18.8,85.1h56l0,0c2.2,0,4-1.8,4-4v-32h-8v28h-48v-48h28v-8h-32l0,0c-2.2,0-4,1.8-4,4v56C14.8,83.3,16.6,85.1,18.8,85.1z"></path> <polygon fill="currentColor" points="45.7,48.7 51.3,54.3 77.2,28.5 77.2,37.2 85.2,37.2 85.2,14.9 62.8,14.9 62.8,22.9 71.5,22.9"></polygon></svg> <span class="sr-only">(opens new window)</span></span></a></li> <li>波兰式和逆波兰式-理论：<a href="http://www.cnblogs.com/chenying99/p/3675876.html" target="_blank" rel="noopener noreferrer">http://www.cnblogs.com/chenying99/p/3675876.html<span><svg xmlns="http://www.w3.org/2000/svg" aria-hidden="true" focusable="false" x="0px" y="0px" viewBox="0 0 100 100" width="15" height="15" class="icon outbound"><path fill="currentColor" d="M18.8,85.1h56l0,0c2.2,0,4-1.8,4-4v-32h-8v28h-48v-48h28v-8h-32l0,0c-2.2,0-4,1.8-4,4v56C14.8,83.3,16.6,85.1,18.8,85.1z"></path> <polygon fill="currentColor" points="45.7,48.7 51.3,54.3 77.2,28.5 77.2,37.2 85.2,37.2 85.2,14.9 62.8,14.9 62.8,22.9 71.5,22.9"></polygon></svg> <span class="sr-only">(opens new window)</span></span></a></li> <li>波兰式和逆波兰式-源码：<a href="https://github.com/Tairraos/rpn.js/blob/master/rpn.js" target="_blank" rel="noopener noreferrer">https://github.com/Tairraos/rpn.js/blob/master/rpn.js<span><svg xmlns="http://www.w3.org/2000/svg" aria-hidden="true" focusable="false" x="0px" y="0px" viewBox="0 0 100 100" width="15" height="15" class="icon outbound"><path fill="currentColor" d="M18.8,85.1h56l0,0c2.2,0,4-1.8,4-4v-32h-8v28h-48v-48h28v-8h-32l0,0c-2.2,0-4,1.8-4,4v56C14.8,83.3,16.6,85.1,18.8,85.1z"></path> <polygon fill="currentColor" points="45.7,48.7 51.3,54.3 77.2,28.5 77.2,37.2 85.2,37.2 85.2,14.9 62.8,14.9 62.8,22.9 71.5,22.9"></polygon></svg> <span class="sr-only">(opens new window)</span></span></a></li></ul> <h2 id="什么是哈希表"><a href="#什么是哈希表" class="header-anchor">#</a> 什么是哈希表？</h2> <p>散列表（也叫哈希表），是根据关键码值直接进行访问的数据结构。也就是说，它通过把关键码值映射到表中一个位置来访问记录，以加快查找的速度。这个映射函数叫做散列函数，存放记录的数组叫做散列表。</p> <h2 id="实例"><a href="#实例" class="header-anchor">#</a> 实例</h2> <h3 id="数组去重"><a href="#数组去重" class="header-anchor">#</a> 数组去重</h3> <div class="language-javascript extra-class"><pre class="language-javascript"><code><span class="token comment">/*
 * 1. ES6：set
 * 2. 循环比较
 * 3. 对象键值对
 * 4. 比较相邻项 
 */</span>
<span class="token comment">/* 第一种：ES6: SET */</span>
<span class="token keyword">const</span> newArr <span class="token operator">=</span> <span class="token punctuation">[</span><span class="token operator">...</span><span class="token keyword">new</span> <span class="token class-name">Set</span><span class="token punctuation">(</span>arr<span class="token punctuation">)</span><span class="token punctuation">]</span><span class="token punctuation">;</span> <span class="token comment">// Array.from(new Set(arr))</span>

<span class="token comment">/* 第二种：当前项与后面的内容比较 */</span>
<span class="token comment">// 1. splice删除当前项，i--；splice会改变原数组，存在数组塌陷问题</span>
<span class="token comment">// 2. 定义一个新数组newArr = [...arr]，删除新数组newArr.splice(i, 1);</span>
<span class="token comment">// 3. 定义一个空数组，i&lt;arr.length，将不包含的push进去</span>
<span class="token comment">// 4. 将当前项置为null，最后再把null删掉，arr[i]=null，arr = arr.filter(item =&gt; item !== null)</span>
<span class="token comment">// 5. 将最后一项替换当前项arr[i]=arr[arr.length-1]，删除最后一项arr.length--，还从当强项循环比较i--；</span>
<span class="token keyword">let</span> newArr <span class="token operator">=</span> <span class="token punctuation">[</span><span class="token operator">...</span>arr<span class="token punctuation">]</span><span class="token punctuation">;</span> <span class="token comment">// 浅克隆，但每个数组都是一个堆，性能不好</span>
<span class="token keyword">for</span><span class="token punctuation">(</span><span class="token keyword">let</span> i<span class="token operator">=</span><span class="token number">0</span><span class="token punctuation">;</span>i<span class="token operator">&lt;</span>arr<span class="token punctuation">.</span>length<span class="token operator">-</span><span class="token number">1</span><span class="token punctuation">;</span>i<span class="token operator">++</span><span class="token punctuation">)</span><span class="token punctuation">{</span>
    <span class="token keyword">let</span> item <span class="token operator">=</span> arr<span class="token punctuation">[</span>i<span class="token punctuation">]</span><span class="token punctuation">,</span>
        args <span class="token operator">=</span> arr<span class="token punctuation">.</span><span class="token function">slice</span><span class="token punctuation">(</span>i <span class="token operator">+</span> <span class="token number">1</span><span class="token punctuation">)</span><span class="token punctuation">;</span> <span class="token comment">// 除当前项的剩余所有项</span>
    <span class="token keyword">if</span><span class="token punctuation">(</span>args<span class="token punctuation">,</span><span class="token function">indexOf</span><span class="token punctuation">(</span>item<span class="token punctuation">)</span> <span class="token operator">&gt;</span> <span class="token operator">-</span><span class="token number">1</span><span class="token punctuation">)</span><span class="token punctuation">{</span> <span class="token comment">// 判断在剩余所有项中是否有当前项，// ES6: includes</span>
        <span class="token comment">// 删除当前项</span>
        <span class="token comment">/* arr.splice(i, 1); 
        i--;*/</span>
        <span class="token comment">// newArr.splice(i, 1);</span>
        <span class="token comment">// arr[i] = null</span>
        arr<span class="token punctuation">[</span>i<span class="token punctuation">]</span><span class="token operator">=</span>arr<span class="token punctuation">[</span>arr<span class="token punctuation">.</span>length<span class="token operator">-</span><span class="token number">1</span><span class="token punctuation">]</span><span class="token punctuation">;</span>
        arr<span class="token punctuation">.</span>length<span class="token operator">--</span><span class="token punctuation">;</span>
        i<span class="token operator">--</span><span class="token punctuation">;</span>
    <span class="token punctuation">}</span><span class="token keyword">else</span><span class="token punctuation">{</span>
        <span class="token comment">// newArr.push(item);</span>
    <span class="token punctuation">}</span>
<span class="token punctuation">}</span>
<span class="token comment">// arr = arr.filter(item =&gt; item !== null)</span>

<span class="token comment">/* 第三种：对象键值对 */</span>
<span class="token keyword">let</span> obj <span class="token operator">=</span> <span class="token punctuation">{</span><span class="token punctuation">}</span><span class="token punctuation">;</span>
<span class="token keyword">for</span><span class="token punctuation">(</span><span class="token keyword">let</span> i <span class="token operator">=</span><span class="token number">0</span><span class="token punctuation">;</span>i<span class="token operator">&lt;</span>arr<span class="token punctuation">.</span>length<span class="token punctuation">;</span>i<span class="token operator">++</span><span class="token punctuation">)</span><span class="token punctuation">{</span>
    <span class="token keyword">let</span> item <span class="token operator">=</span> arr<span class="token punctuation">[</span>i<span class="token punctuation">]</span><span class="token punctuation">;</span>
    <span class="token keyword">if</span><span class="token punctuation">(</span><span class="token keyword">typeof</span> obj<span class="token punctuation">[</span>item<span class="token punctuation">]</span><span class="token punctuation">)</span><span class="token punctuation">{</span>
        arr<span class="token punctuation">[</span>i<span class="token punctuation">]</span><span class="token operator">=</span>arr<span class="token punctuation">[</span>arr<span class="token punctuation">.</span>length<span class="token operator">-</span><span class="token number">1</span><span class="token punctuation">]</span><span class="token punctuation">;</span>
        arr<span class="token punctuation">.</span>length<span class="token operator">--</span><span class="token punctuation">;</span>
        i<span class="token operator">--</span><span class="token punctuation">;</span>
        <span class="token keyword">continue</span><span class="token punctuation">;</span>
    <span class="token punctuation">}</span>
    obj<span class="token punctuation">[</span>item<span class="token punctuation">]</span> <span class="token operator">=</span> item<span class="token punctuation">;</span>
<span class="token punctuation">}</span>
obj <span class="token operator">=</span> <span class="token keyword">null</span><span class="token punctuation">;</span> <span class="token comment">// 最后销毁obj这个堆</span>

<span class="token comment">/* 第四种：先排序，比较相邻项（基于正则） */</span>
arr<span class="token punctuation">.</span><span class="token function">sort</span><span class="token punctuation">(</span><span class="token punctuation">(</span><span class="token parameter">a<span class="token punctuation">,</span> b</span><span class="token punctuation">)</span> <span class="token operator">=&gt;</span> a<span class="token operator">-</span>b<span class="token punctuation">)</span><span class="token punctuation">;</span>
arr <span class="token operator">=</span> arr<span class="token punctuation">.</span><span class="token function">join</span><span class="token punctuation">(</span><span class="token string">'@'</span><span class="token punctuation">)</span> <span class="token operator">+</span> <span class="token string">'@'</span><span class="token punctuation">;</span> <span class="token comment">// 每个数字后面加上'@'，10@10@10@10@10@</span>
<span class="token keyword">let</span> reg <span class="token operator">=</span> <span class="token regex"><span class="token regex-delimiter">/</span><span class="token regex-source language-regex">(\d+@)\1*</span><span class="token regex-delimiter">/</span><span class="token regex-flags">g</span></span><span class="token punctuation">,</span>
 arr <span class="token operator">=</span> <span class="token punctuation">[</span><span class="token punctuation">]</span><span class="token punctuation">;</span>
arr<span class="token punctuation">.</span><span class="token function">replace</span><span class="token punctuation">(</span>reg<span class="token punctuation">,</span> <span class="token punctuation">(</span><span class="token parameter">n<span class="token punctuation">,</span> m</span><span class="token punctuation">)</span> <span class="token operator">=&gt;</span> <span class="token punctuation">{</span> <span class="token comment">// m：不重复的10@</span>
 <span class="token comment">// arr.push(Number(m.slice(0, m.length-1)));</span>
    arr<span class="token punctuation">.</span><span class="token function">push</span><span class="token punctuation">(</span><span class="token function">parseFloat</span><span class="token punctuation">(</span>m<span class="token punctuation">)</span><span class="token punctuation">)</span><span class="token punctuation">;</span> <span class="token comment">// 可以直接拿到字符串中的数字部分</span>
<span class="token punctuation">}</span><span class="token punctuation">)</span>
</code></pre></div><h3 id="数组排序"><a href="#数组排序" class="header-anchor">#</a> 数组排序</h3> <ul><li>快速排序：<a href="https://segmentfault.com/a/1190000009426421" target="_blank" rel="noopener noreferrer">https://segmentfault.com/a/1190000009426421<span><svg xmlns="http://www.w3.org/2000/svg" aria-hidden="true" focusable="false" x="0px" y="0px" viewBox="0 0 100 100" width="15" height="15" class="icon outbound"><path fill="currentColor" d="M18.8,85.1h56l0,0c2.2,0,4-1.8,4-4v-32h-8v28h-48v-48h28v-8h-32l0,0c-2.2,0-4,1.8-4,4v56C14.8,83.3,16.6,85.1,18.8,85.1z"></path> <polygon fill="currentColor" points="45.7,48.7 51.3,54.3 77.2,28.5 77.2,37.2 85.2,37.2 85.2,14.9 62.8,14.9 62.8,22.9 71.5,22.9"></polygon></svg> <span class="sr-only">(opens new window)</span></span></a></li> <li>选择排序：<a href="https://segmentfault.com/a/1190000009366805" target="_blank" rel="noopener noreferrer">https://segmentfault.com/a/1190000009366805<span><svg xmlns="http://www.w3.org/2000/svg" aria-hidden="true" focusable="false" x="0px" y="0px" viewBox="0 0 100 100" width="15" height="15" class="icon outbound"><path fill="currentColor" d="M18.8,85.1h56l0,0c2.2,0,4-1.8,4-4v-32h-8v28h-48v-48h28v-8h-32l0,0c-2.2,0-4,1.8-4,4v56C14.8,83.3,16.6,85.1,18.8,85.1z"></path> <polygon fill="currentColor" points="45.7,48.7 51.3,54.3 77.2,28.5 77.2,37.2 85.2,37.2 85.2,14.9 62.8,14.9 62.8,22.9 71.5,22.9"></polygon></svg> <span class="sr-only">(opens new window)</span></span></a></li> <li>希尔排序：<a href="https://segmentfault.com/a/1190000009461832" target="_blank" rel="noopener noreferrer">https://segmentfault.com/a/1190000009461832<span><svg xmlns="http://www.w3.org/2000/svg" aria-hidden="true" focusable="false" x="0px" y="0px" viewBox="0 0 100 100" width="15" height="15" class="icon outbound"><path fill="currentColor" d="M18.8,85.1h56l0,0c2.2,0,4-1.8,4-4v-32h-8v28h-48v-48h28v-8h-32l0,0c-2.2,0-4,1.8-4,4v56C14.8,83.3,16.6,85.1,18.8,85.1z"></path> <polygon fill="currentColor" points="45.7,48.7 51.3,54.3 77.2,28.5 77.2,37.2 85.2,37.2 85.2,14.9 62.8,14.9 62.8,22.9 71.5,22.9"></polygon></svg> <span class="sr-only">(opens new window)</span></span></a></li></ul> <p>冒泡排序：两两比较，将小的放前面，共比较arr.length-1轮，大的放后面，每一轮当前项和后一项比较，当前数组中最大的放到末尾</p> <div class="language-javascript extra-class"><pre class="language-javascript"><code><span class="token keyword">function</span> <span class="token function">bubble</span><span class="token punctuation">(</span><span class="token parameter">arr</span><span class="token punctuation">)</span> <span class="token punctuation">{</span>
    <span class="token keyword">let</span> temp <span class="token operator">=</span> <span class="token keyword">null</span><span class="token punctuation">;</span>
    <span class="token keyword">for</span><span class="token punctuation">(</span><span class="token keyword">let</span> i<span class="token operator">=</span><span class="token number">0</span><span class="token punctuation">;</span>i<span class="token operator">&gt;</span>arr<span class="token punctuation">.</span>length<span class="token operator">-</span><span class="token number">1</span><span class="token punctuation">;</span>i<span class="token operator">++</span><span class="token punctuation">)</span><span class="token punctuation">{</span>
        <span class="token keyword">for</span><span class="token punctuation">(</span><span class="token keyword">let</span> j<span class="token operator">=</span><span class="token number">0</span><span class="token punctuation">;</span>j<span class="token operator">&gt;</span>arr<span class="token punctuation">.</span>length<span class="token operator">-</span><span class="token number">1</span><span class="token operator">-</span>i<span class="token punctuation">;</span>j<span class="token operator">++</span><span class="token punctuation">)</span><span class="token punctuation">{</span>
         <span class="token keyword">if</span><span class="token punctuation">(</span>arr<span class="token punctuation">[</span>j<span class="token punctuation">]</span> <span class="token operator">&gt;</span> arr<span class="token punctuation">[</span>j<span class="token operator">+</span><span class="token number">1</span><span class="token punctuation">]</span><span class="token punctuation">)</span><span class="token punctuation">{</span>
              temp <span class="token operator">=</span> arr<span class="token punctuation">[</span>j<span class="token punctuation">]</span><span class="token punctuation">;</span>
                arr<span class="token punctuation">[</span>j<span class="token punctuation">]</span> <span class="token operator">=</span> arr<span class="token punctuation">[</span>j<span class="token operator">+</span><span class="token number">1</span><span class="token punctuation">]</span><span class="token punctuation">;</span>
                arr<span class="token punctuation">[</span>j<span class="token operator">+</span><span class="token number">1</span><span class="token punctuation">]</span> <span class="token operator">=</span> temp<span class="token punctuation">;</span>
             <span class="token punctuation">}</span>
     <span class="token punctuation">}</span>
    <span class="token punctuation">}</span>
    <span class="token keyword">return</span> arr<span class="token punctuation">;</span>
<span class="token punctuation">}</span>
</code></pre></div><p>插入排序：</p> <div class="language-javascript extra-class"><pre class="language-javascript"><code><span class="token keyword">function</span> <span class="token function">insert</span><span class="token punctuation">(</span><span class="token parameter">arr</span><span class="token punctuation">)</span><span class="token punctuation">{</span>
    <span class="token keyword">let</span> handle <span class="token operator">=</span> <span class="token punctuation">[</span><span class="token punctuation">]</span><span class="token punctuation">;</span>
    handle<span class="token punctuation">.</span><span class="token function">push</span><span class="token punctuation">(</span>arr<span class="token punctuation">[</span><span class="token number">0</span><span class="token punctuation">]</span><span class="token punctuation">)</span><span class="token punctuation">;</span>
    <span class="token keyword">for</span><span class="token punctuation">(</span><span class="token keyword">let</span> i<span class="token operator">=</span><span class="token number">0</span><span class="token punctuation">;</span>i<span class="token operator">&lt;</span>arr<span class="token punctuation">.</span>length<span class="token punctuation">;</span>i<span class="token operator">++</span><span class="token punctuation">)</span><span class="token punctuation">{</span>
        <span class="token keyword">let</span> <span class="token constant">A</span> <span class="token operator">=</span> arr<span class="token punctuation">[</span>i<span class="token punctuation">]</span><span class="token punctuation">;</span>
        <span class="token keyword">for</span><span class="token punctuation">(</span><span class="token keyword">let</span> j<span class="token operator">=</span>handle<span class="token punctuation">.</span>length <span class="token operator">-</span><span class="token number">1</span><span class="token punctuation">;</span>j<span class="token operator">&gt;=</span><span class="token number">0</span><span class="token punctuation">;</span>j<span class="token operator">--</span><span class="token punctuation">)</span><span class="token punctuation">{</span>
            <span class="token keyword">let</span> <span class="token constant">B</span> <span class="token operator">=</span> handle<span class="token punctuation">[</span>j<span class="token punctuation">]</span><span class="token punctuation">;</span>
            <span class="token keyword">if</span><span class="token punctuation">(</span><span class="token constant">A</span> <span class="token operator">&gt;</span> <span class="token constant">B</span><span class="token punctuation">)</span><span class="token punctuation">{</span>
                handle<span class="token punctuation">.</span><span class="token function">splice</span><span class="token punctuation">(</span>j<span class="token operator">+</span><span class="token number">1</span><span class="token punctuation">,</span> <span class="token number">0</span><span class="token punctuation">,</span> <span class="token constant">A</span><span class="token punctuation">)</span><span class="token punctuation">;</span>
                <span class="token keyword">break</span><span class="token punctuation">;</span>
            <span class="token punctuation">}</span>
            <span class="token keyword">if</span><span class="token punctuation">(</span>j <span class="token operator">===</span> <span class="token number">0</span><span class="token punctuation">)</span><span class="token punctuation">{</span>
              handle<span class="token punctuation">.</span><span class="token function">unshift</span><span class="token punctuation">(</span><span class="token constant">A</span><span class="token punctuation">)</span><span class="token punctuation">;</span>  
             <span class="token punctuation">}</span>
        <span class="token punctuation">}</span>
    <span class="token punctuation">}</span>
<span class="token punctuation">}</span>
</code></pre></div><p>快速排序 - 二分法，性能最好</p> <p>取中间值，分为左小右大两个数组，递归，再左右拼接</p> <div class="language-javascript extra-class"><pre class="language-javascript"><code><span class="token keyword">function</span> <span class="token function">quick</span><span class="token punctuation">(</span><span class="token parameter">arr</span><span class="token punctuation">)</span><span class="token punctuation">{</span>
    <span class="token keyword">if</span><span class="token punctuation">(</span>arr<span class="token punctuation">.</span>length <span class="token operator">&lt;=</span> <span class="token number">1</span><span class="token punctuation">)</span> <span class="token keyword">return</span> arr<span class="token punctuation">;</span>
    <span class="token comment">// 1. 找到数组的中间项，在原有的数组中把它移除</span>
    <span class="token keyword">let</span> middleIndex <span class="token operator">=</span> Math<span class="token punctuation">.</span><span class="token function">floor</span><span class="token punctuation">(</span>arr<span class="token punctuation">.</span>length<span class="token operator">/</span><span class="token number">2</span><span class="token punctuation">)</span><span class="token punctuation">;</span>
    <span class="token keyword">let</span> middleValue <span class="token operator">=</span> arr<span class="token punctuation">.</span><span class="token function">splice</span><span class="token punctuation">(</span>middleIndex<span class="token punctuation">,</span> <span class="token number">1</span><span class="token punctuation">)</span><span class="token punctuation">[</span><span class="token number">0</span><span class="token punctuation">]</span><span class="token punctuation">;</span>
    <span class="token comment">// 2. 准备左右两个数组，循环剩下数组中的每一项，比当前项小的放到左数组中，大的放右数组中</span>
    <span class="token keyword">let</span> leftArr <span class="token operator">=</span> <span class="token punctuation">[</span><span class="token punctuation">]</span><span class="token punctuation">,</span>
        rightArr <span class="token operator">=</span> <span class="token punctuation">[</span><span class="token punctuation">]</span><span class="token punctuation">;</span>
    <span class="token keyword">for</span><span class="token punctuation">(</span><span class="token keyword">let</span> i<span class="token operator">=</span><span class="token number">0</span><span class="token punctuation">;</span>i<span class="token operator">&lt;</span>arr<span class="token punctuation">.</span>length<span class="token punctuation">;</span>i<span class="token operator">++</span><span class="token punctuation">)</span><span class="token punctuation">{</span>
        <span class="token keyword">let</span> item <span class="token operator">=</span> arr<span class="token punctuation">[</span>i<span class="token punctuation">]</span><span class="token punctuation">;</span>
        item <span class="token operator">&lt;</span> middleValue <span class="token operator">?</span> leftArr<span class="token punctuation">.</span><span class="token function">push</span><span class="token punctuation">(</span>item<span class="token punctuation">)</span> <span class="token operator">:</span> rightArr<span class="token punctuation">.</span><span class="token function">push</span><span class="token punctuation">(</span>item<span class="token punctuation">)</span><span class="token punctuation">;</span>
    <span class="token punctuation">}</span>
    <span class="token comment">// 3. 递归左右数组，直到全部排完序，再将左+中+右拼接成最后的结果</span>
    <span class="token keyword">return</span> <span class="token function">quick</span><span class="token punctuation">(</span>leftArr<span class="token punctuation">)</span><span class="token punctuation">.</span><span class="token function">concat</span><span class="token punctuation">(</span>middleValue<span class="token punctuation">,</span> <span class="token function">quick</span><span class="token punctuation">(</span>rightArr<span class="token punctuation">)</span><span class="token punctuation">)</span><span class="token punctuation">;</span>
<span class="token punctuation">}</span>
</code></pre></div><h3 id="数组扁平化"><a href="#数组扁平化" class="header-anchor">#</a> 数组扁平化</h3> <p>多维数组降成一维数组</p> <div class="language-javascript extra-class"><pre class="language-javascript"><code><span class="token keyword">var</span> arr <span class="token operator">=</span> <span class="token punctuation">[</span><span class="token number">1</span><span class="token punctuation">,</span> <span class="token punctuation">[</span><span class="token number">2</span><span class="token punctuation">,</span> <span class="token punctuation">[</span><span class="token number">3</span><span class="token punctuation">,</span> <span class="token punctuation">[</span><span class="token number">4</span><span class="token punctuation">,</span> <span class="token punctuation">[</span><span class="token number">5</span><span class="token punctuation">]</span><span class="token punctuation">]</span><span class="token punctuation">]</span><span class="token punctuation">]</span><span class="token punctuation">]</span>
<span class="token comment">/* 第一种：ES6 */</span>
arr <span class="token operator">=</span> arr<span class="token punctuation">.</span><span class="token function">flat</span><span class="token punctuation">(</span>arr<span class="token punctuation">)</span><span class="token punctuation">;</span>

<span class="token comment">/* 第二种：转换为字符串 */</span>
arr <span class="token operator">=</span> aa<span class="token punctuation">.</span><span class="token function">toString</span><span class="token punctuation">(</span><span class="token punctuation">)</span><span class="token punctuation">.</span><span class="token function">split</span><span class="token punctuation">(</span><span class="token string">','</span><span class="token punctuation">)</span><span class="token punctuation">.</span><span class="token function">map</span><span class="token punctuation">(</span><span class="token parameter">item</span> <span class="token operator">=&gt;</span> <span class="token function">Number</span><span class="token punctuation">(</span>item<span class="token punctuation">)</span><span class="token punctuation">)</span><span class="token punctuation">;</span>
arr <span class="token operator">=</span> <span class="token constant">JSON</span><span class="token punctuation">.</span><span class="token function">stringify</span><span class="token punctuation">(</span>arr<span class="token punctuation">)</span><span class="token punctuation">.</span><span class="token function">replace</span><span class="token punctuation">(</span><span class="token regex"><span class="token regex-delimiter">/</span><span class="token regex-source language-regex">(\[|\]\)</span><span class="token regex-delimiter">/</span><span class="token regex-flags">g</span></span><span class="token punctuation">,</span> <span class="token string">''</span><span class="token punctuation">)</span><span class="token punctuation">.</span><span class="token function">split</span><span class="token punctuation">(</span><span class="token string">','</span><span class="token punctuation">)</span><span class="token punctuation">.</span><span class="token function">map</span><span class="token punctuation">(</span><span class="token parameter">item</span> <span class="token operator">=&gt;</span> <span class="token function">Number</span><span class="token punctuation">(</span>item<span class="token punctuation">)</span><span class="token punctuation">)</span><span class="token punctuation">;</span>

<span class="token comment">/* 第三种：基于数组的some方法：循环验证是否为数组 */</span>
<span class="token keyword">while</span> <span class="token punctuation">(</span>arr<span class="token punctuation">.</span><span class="token function">some</span><span class="token punctuation">(</span><span class="token parameter">item</span> <span class="token operator">=&gt;</span> Array<span class="token punctuation">.</span><span class="token function">isArray</span><span class="token punctuation">(</span>item<span class="token punctuation">)</span><span class="token punctuation">)</span><span class="token punctuation">)</span><span class="token punctuation">{</span>
    arr <span class="token operator">=</span> <span class="token punctuation">[</span><span class="token punctuation">]</span><span class="token punctuation">.</span><span class="token function">concat</span><span class="token punctuation">(</span><span class="token operator">...</span>arr<span class="token punctuation">)</span><span class="token punctuation">;</span> <span class="token comment">// 降一维</span>
<span class="token punctuation">}</span>

<span class="token comment">/* 第四种：递归 */</span>
<span class="token keyword">function</span> <span class="token function">myFlat</span><span class="token punctuation">(</span><span class="token parameter">arr</span><span class="token punctuation">)</span><span class="token punctuation">{</span>
    <span class="token keyword">let</span> result <span class="token operator">=</span> <span class="token punctuation">[</span><span class="token punctuation">]</span><span class="token punctuation">;</span>
    <span class="token keyword">function</span> <span class="token function">fn</span><span class="token punctuation">(</span><span class="token parameter">newArr</span><span class="token punctuation">)</span><span class="token punctuation">{</span>
        <span class="token keyword">for</span><span class="token punctuation">(</span><span class="token keyword">let</span> i<span class="token operator">=</span><span class="token number">0</span><span class="token punctuation">;</span>i<span class="token operator">&lt;</span>newArr<span class="token punctuation">.</span>length<span class="token punctuation">;</span>i<span class="token operator">++</span><span class="token punctuation">)</span><span class="token punctuation">{</span>
            <span class="token keyword">let</span> item <span class="token operator">=</span> newArr<span class="token punctuation">[</span>i<span class="token punctuation">]</span><span class="token punctuation">;</span>
            <span class="token keyword">if</span><span class="token punctuation">(</span>Array<span class="token punctuation">.</span><span class="token function">isArray</span><span class="token punctuation">(</span>item<span class="token punctuation">)</span><span class="token punctuation">)</span><span class="token punctuation">{</span>
               <span class="token function">fn</span><span class="token punctuation">(</span>item<span class="token punctuation">)</span><span class="token punctuation">;</span>
                <span class="token keyword">continue</span><span class="token punctuation">;</span>
            <span class="token punctuation">}</span>
            result<span class="token punctuation">.</span><span class="token function">push</span><span class="token punctuation">(</span>item<span class="token punctuation">)</span><span class="token punctuation">;</span>
        <span class="token punctuation">}</span>
    <span class="token punctuation">}</span>
    <span class="token function">fn</span><span class="token punctuation">(</span>arr<span class="token punctuation">)</span><span class="token punctuation">;</span>
    <span class="token keyword">return</span> result<span class="token punctuation">;</span>
<span class="token punctuation">}</span>
</code></pre></div><h3 id="斐波那契数列-阿里"><a href="#斐波那契数列-阿里" class="header-anchor">#</a> * 斐波那契数列（阿里）</h3> <p>斐波那契额数列为：[1, 1, 2, 3, 5, 8, 13, 21, ...]。当index &gt; 1时，当前项是前两项之和</p> <div class="language-javascript extra-class"><pre class="language-javascript"><code><span class="token keyword">function</span> <span class="token function">fibonacci</span><span class="token punctuation">(</span><span class="token parameter">n</span><span class="token punctuation">)</span> <span class="token punctuation">{</span>
    <span class="token keyword">function</span> <span class="token function">fn</span><span class="token punctuation">(</span><span class="token parameter">n<span class="token punctuation">,</span> cur <span class="token operator">=</span> <span class="token number">1</span><span class="token punctuation">,</span> next <span class="token operator">=</span> <span class="token number">1</span></span><span class="token punctuation">)</span><span class="token punctuation">{</span>
        <span class="token keyword">if</span><span class="token punctuation">(</span>n <span class="token operator">==</span> <span class="token number">0</span><span class="token punctuation">)</span> <span class="token keyword">return</span> cur<span class="token punctuation">;</span>
        <span class="token keyword">return</span> <span class="token function">fn</span><span class="token punctuation">(</span>n<span class="token operator">-</span><span class="token number">1</span><span class="token punctuation">,</span> next<span class="token punctuation">,</span> cur <span class="token operator">+</span> next<span class="token punctuation">)</span><span class="token punctuation">;</span>
    <span class="token punctuation">}</span>
    <span class="token keyword">return</span> <span class="token function">fn</span><span class="token punctuation">(</span>n<span class="token punctuation">)</span><span class="token punctuation">;</span>
<span class="token punctuation">}</span>
<span class="token keyword">function</span> <span class="token function">fibonacci1</span><span class="token punctuation">(</span><span class="token parameter">n</span><span class="token punctuation">)</span> <span class="token punctuation">{</span>
    <span class="token keyword">if</span><span class="token punctuation">(</span>n <span class="token operator">&lt;=</span> <span class="token number">1</span><span class="token punctuation">)</span> <span class="token keyword">return</span> <span class="token number">1</span><span class="token punctuation">;</span>
    <span class="token keyword">let</span> arr <span class="token operator">=</span> <span class="token punctuation">[</span><span class="token number">1</span><span class="token punctuation">,</span> <span class="token number">1</span><span class="token punctuation">]</span><span class="token punctuation">;</span>
    <span class="token keyword">let</span> i <span class="token operator">=</span> n <span class="token operator">+</span> <span class="token number">1</span> <span class="token operator">-</span><span class="token number">2</span><span class="token punctuation">;</span> <span class="token comment">// 即将要创建多少个</span>
    <span class="token function">white</span><span class="token punctuation">(</span><span class="token parameter">i<span class="token operator">&gt;</span><span class="token number">0</span></span><span class="token punctuation">)</span><span class="token punctuation">{</span>
        <span class="token keyword">let</span> a <span class="token operator">=</span> arr<span class="token punctuation">[</span>arr<span class="token punctuation">.</span>length <span class="token operator">-</span><span class="token number">2</span><span class="token punctuation">]</span><span class="token punctuation">;</span>
         b <span class="token operator">=</span> arr<span class="token punctuation">[</span>arr<span class="token punctuation">.</span>length <span class="token operator">-</span><span class="token number">1</span><span class="token punctuation">]</span><span class="token punctuation">;</span>
        arr<span class="token punctuation">.</span><span class="token function">push</span><span class="token punctuation">(</span>a <span class="token operator">+</span> b<span class="token punctuation">)</span><span class="token punctuation">;</span>
        i<span class="token operator">--</span><span class="token punctuation">;</span>
    <span class="token punctuation">}</span>
    <span class="token keyword">return</span> arr<span class="token punctuation">[</span>arr<span class="token punctuation">.</span>length <span class="token operator">-</span><span class="token number">1</span><span class="token punctuation">]</span><span class="token punctuation">;</span>
<span class="token punctuation">}</span>
</code></pre></div><h3 id="输出所有和是n的连续正数序列-头条"><a href="#输出所有和是n的连续正数序列-头条" class="header-anchor">#</a> 输出所有和是N的连续正数序列（头条）</h3> <p>例如：输入15，返回[[1, 2, 3, 4, 5], [4, 5, 6], [7, 8]]</p> <div class="language-javascript extra-class"><pre class="language-javascript"><code><span class="token comment">// 从N开始计算连续M个的正数序列和 - 等差数列求和（(首+尾)*个数/2）</span>
<span class="token keyword">function</span> <span class="token function">fn</span><span class="token punctuation">(</span><span class="token parameter">n</span><span class="token punctuation">)</span><span class="token punctuation">{</span>
    <span class="token keyword">let</span> result <span class="token operator">=</span> <span class="token punctuation">[</span><span class="token punctuation">]</span><span class="token punctuation">;</span>
    <span class="token keyword">let</span> middle <span class="token operator">=</span> Math<span class="token punctuation">.</span><span class="token function">ceil</span><span class="token punctuation">(</span>n<span class="token operator">/</span><span class="token number">2</span><span class="token punctuation">)</span><span class="token punctuation">;</span> <span class="token comment">// 只有小于当前值的累加，才可能等于当前值</span>
    <span class="token keyword">for</span><span class="token punctuation">(</span><span class="token keyword">let</span> i<span class="token operator">=</span><span class="token number">0</span><span class="token punctuation">;</span> i<span class="token operator">&lt;</span>middle<span class="token punctuation">;</span>i<span class="token operator">++</span><span class="token punctuation">)</span><span class="token punctuation">{</span> <span class="token comment">// 从1开始累加</span>
        <span class="token keyword">for</span><span class="token punctuation">(</span><span class="token keyword">let</span> j<span class="token operator">=</span><span class="token number">2</span><span class="token punctuation">;</span><span class="token punctuation">;</span>j<span class="token operator">++</span><span class="token punctuation">)</span><span class="token punctuation">{</span> <span class="token comment">// 累加多少次</span>
            <span class="token keyword">let</span> total <span class="token operator">=</span> <span class="token punctuation">(</span>i<span class="token operator">+</span><span class="token punctuation">(</span>i<span class="token operator">+</span>j<span class="token operator">-</span><span class="token number">1</span><span class="token punctuation">)</span><span class="token operator">*</span>j<span class="token operator">/</span><span class="token number">2</span><span class="token punctuation">;</span> <span class="token comment">// 累加和</span>
            <span class="token keyword">if</span><span class="token punctuation">(</span>total <span class="token operator">&gt;</span> n<span class="token punctuation">)</span> <span class="token punctuation">{</span>
                <span class="token keyword">break</span><span class="token punctuation">;</span>
            <span class="token punctuation">}</span><span class="token keyword">else</span> <span class="token keyword">if</span><span class="token punctuation">(</span>total <span class="token operator">===</span> n<span class="token punctuation">)</span><span class="token punctuation">{</span>
                result<span class="token punctuation">.</span><span class="token function">push</span><span class="token punctuation">(</span><span class="token function">createArr</span><span class="token punctuation">(</span>i<span class="token punctuation">,</span> j<span class="token punctuation">)</span><span class="token punctuation">)</span><span class="token punctuation">;</span>
                <span class="token keyword">break</span><span class="token punctuation">;</span> 
            <span class="token punctuation">}</span>
        <span class="token punctuation">}</span>
    <span class="token punctuation">}</span>
    <span class="token keyword">return</span> result<span class="token punctuation">;</span>
<span class="token punctuation">}</span>
<span class="token keyword">function</span> <span class="token function">createArr</span><span class="token punctuation">(</span><span class="token parameter">n<span class="token punctuation">,</span> len</span><span class="token punctuation">)</span><span class="token punctuation">{</span>
    <span class="token keyword">let</span> arr <span class="token operator">=</span> <span class="token keyword">new</span> <span class="token class-name">Array</span><span class="token punctuation">(</span>len<span class="token punctuation">)</span><span class="token punctuation">.</span><span class="token function">fill</span><span class="token punctuation">(</span><span class="token keyword">null</span><span class="token punctuation">)</span><span class="token punctuation">,</span>
        temp <span class="token operator">=</span> <span class="token punctuation">[</span><span class="token punctuation">]</span><span class="token punctuation">;</span>
    arr<span class="token punctuation">[</span><span class="token number">0</span><span class="token punctuation">]</span> <span class="token operator">=</span> n<span class="token punctuation">;</span>
    arr <span class="token operator">=</span> arr<span class="token punctuation">.</span><span class="token function">map</span><span class="token punctuation">(</span><span class="token punctuation">(</span><span class="token parameter">item<span class="token punctuation">,</span> index</span><span class="token punctuation">)</span> <span class="token operator">=&gt;</span> <span class="token punctuation">{</span>
        <span class="token keyword">if</span><span class="token punctuation">(</span>item <span class="token operator">===</span> <span class="token keyword">null</span><span class="token punctuation">)</span> <span class="token punctuation">{</span>
            item <span class="token operator">=</span> temp<span class="token punctuation">[</span>index<span class="token operator">-</span><span class="token number">1</span><span class="token punctuation">]</span> <span class="token operator">+</span> <span class="token number">1</span><span class="token punctuation">;</span>
        <span class="token punctuation">}</span>
        temp<span class="token punctuation">.</span><span class="token function">push</span><span class="token punctuation">(</span>item<span class="token punctuation">)</span><span class="token punctuation">;</span>
        <span class="token keyword">return</span> item<span class="token punctuation">;</span>
    <span class="token punctuation">}</span><span class="token punctuation">)</span>
    <span class="token keyword">return</span> arr<span class="token punctuation">;</span>
<span class="token punctuation">}</span>
</code></pre></div><h3 id="最大蓄水池问题"><a href="#最大蓄水池问题" class="header-anchor">#</a> 最大蓄水池问题</h3> <div class="language-javascript extra-class"><pre class="language-javascript"><code>
</code></pre></div></div> <footer class="page-edit"><!----> <div class="last-updated"><span class="prefix">更新时间:</span> <span class="time">2/21/2022, 7:01:02 PM</span></div></footer> <div class="page-nav"><p class="inner"><span class="prev">
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